1. Field of the Invention
The present invention relates to synthesizing a real image and a created image.
2. Description of the Related Art
A telescope placed at an observation platform or the like captures a scene viewed from the platform, optically enlarges and presents it to a user. A telescope optically enlarges a scene and presents it to a user so that it can present only an object existing in a real world. For example, a telescope can neither present information such as an address and a name of a building existing in the real world nor provide the real world with virtual characters.
The following related art solving such problems is known.
Japanese Patent No. 2833206 “Display at Observation Platform” discloses techniques of synthesizing a real scene taken with a telescope and virtual characters and images. The display disclosed in this patent synthesizes real world light in front of the display and image display light from a plane on which virtual characters and images are displayed by using a combiner constituted of a half mirror and the like, and presents the synthetic image to a user. The techniques of displaying a real world image and a computer generated image synthesized by a half mirror and the like are called an optical see-through display method.
There is another conventional system in which a HMD (head mount display) with a built-in camera is mounted on a head and real scenes captured while the HMD is moved as the head moves and computer images are synthesized. The techniques of displaying a scene image photographed with a camera and an image generated by a computer or the like synthesized together are called a video see-through display method.
With both the optical see-through and video see-through display methods, a zoom lens is sometimes used for enlarging a real world scene. Most of such zoom lenses are equipped with a mechanism for adjusting a focus. The focus is adjusted manually by a user viewing a scene through a display apparatus or automatically with an auto focussing mechanism.
It is, however, difficult to adjust the focus of a zoom lens to a virtual character displayed in a real world scene. With the auto focussing mechanism, the focus is adjusted always to a real world scene beyond virtual characters, and it is impossible to adjust the focus to the virtual characters. This point has been desired to be improved.